add mtime to served images in gallery to prevent cache from showing old images

modules/ui_tempdir.py

@@ -36,7 +36,7 @@ def save_pil_to_file(pil_image, dir=None):
     if already_saved_as and os.path.isfile(already_saved_as):
         register_tmp_file(shared.demo, already_saved_as)
 
-        file_obj = Savedfile(already_saved_as)
+        file_obj = Savedfile(f"{already_saved_as}?{os.path.getmtime(already_saved_as)}")
         return file_obj
 
     if shared.opts.temp_dir != "":